1. Field of the Invention
The present invention relates to a charging/discharging electrical energy indication apparatus and, more particularly, to such a charging/discharging electrical energy indication apparatus and its indication method that accurately calculates the amount of electrical power of the storage battery, and indications the result by digits. The invention relates also to an electrical power calculation method for use in the charging/discharging electrical energy indication apparatus.
2. Description of the Related Art
Following fast development of high-tech, a variety of mobile high-tech products including notebook computers, mobile telephones, CD players, PDAs, VCD players, and etc. have been disclosed and have appeared on the market. These mobile electronic apparatus commonly use storage battery to provide the necessary working voltage. In order to prevent data loss due to power low, a mobile electronic apparatus generally has means to detect and indication the residual electrical power of the equipped storage battery. However, the indication of the battery power of regular mobile electronic apparatus is simply a rough indication expressed by percentage or step but not an accurate indication expressed by digits.
Further, when charging a battery with a conventional battery charger, the battery chargers does not show the amount charged or the residual amount of electrical power of the battery. According to conventional techniques, the charging methods of conventional battery chargers include:
1. Constant voltage charging method: According to this method, the battery charger provides the battery with a constant voltage power source, i.e., the charging current is automatically stopped when the battery charged to the voltage level of the constant voltage power source.
2. Constant current charging method: This method is superior to the constant voltage charging method because it provides the battery with stabilized current. However, the cost of the charging circuit is relatively high because the charging circuit must be provided with a voltage detecting circuit that cuts off charging power when the end voltage of the battery reached the rated voltage value.
3. Pulse charging method: This method uses pulse power to charge the battery, activating the chemical characteristics of the battery and prolonging the service life of the battery.
A battery charger made subject to either of the aforesaid methods stops charging the battery subject to the condition that the end voltage of the battery reached the rated voltage value, i.e., the charging procedure is stopped when the end voltage of the battery reached the rated voltage value. However, because the initial voltage value is unknown, the actual amount of charging power entered the battery at each charging action is unknown. Because the actual condition of the battery is unknown, the user may not take the necessary battery discharging action, or may charge the battery that is not necessary to be charged. Because regular battery chargers cannot indicate the amount of electrical power of the battery when charging, the user may neglect xe2x80x9cbattery agingxe2x80x9d or xe2x80x9cbattery memory effectxe2x80x9d.
The present invention has been accomplished under the circumstances in view. It is therefore the main object of the present invention to provide a charging/discharging electrical energy indication apparatus that accurately calculates the amount of electrical power of the battery. It is another object of the present invention to provide a charging/discharging electrical energy indication apparatus that indicates the residual amount of electrical power of the battery when charging. It is still another object of the present invention to provide a charging/discharging electrical energy indication apparatus that indicates the accumulated amount of electrical power of the battery when charging. To achieve these and other objects of the present invention, the electrical energy calculation method is to sample charging/discharging current and end voltage of the battery at a fixed cycle, and then to calculate the electrical energy value of every charging/discharging sampling subject to W=(P0+P1)T/2. By means of continuously adding or deducting the electrical energy value of every charging/discharging sampling, the charging electrical energy of the battery is obtained and displayed by digits. The method is used in a charging/discharging electrical energy indication apparatus, enabling the user to know the charging amount of electrical energy at every charging action for reference. Therefore, the user knows when to discharge the battery. When the invention used in an electronic apparatus, the user can accurately known the charging power and consumption power of the battery at every charging action,